Cure system composition and a method for curing chlorinated elastomer compositions

ABSTRACT

The instant invention is an improved cure system composition and a method for curing chlorinated elastomer compositions. The cure system composition includes a polymercapto crosslinking agent; an inorganic base; and an onium salt. The onium salt has a formula selected from the group consisting of formula (I) and formula (II); wherein Z is a nitrogen or phosphorous atom, R1 to R4 are independently alkyl or aryl groups containing between 2 and 8 carbon atoms, and the total number of carbon atoms on R1-R4 is between 10 and 14; wherein R5 and R6 are alkyl groups containing between 1 and 8 carbon atoms, and the total number of carbon atoms on R5-R6 being between 5 and 9; and wherein X is an anion. The method for curing a chlorinated elastomer composition according to instant invention includes the following steps: (1) providing a chlorinated elastomer composition; (2) providing a cure system composition as described above; (3) contacting said chlorinated elastomer composition with said cure system composition; and (4) thereby curing said chlorinated elastomer composition.

This application is claiming priority from U.S. Provisional ApplicationSer. No. 60/661,594, filed on Mar. 14, 2005 entitled “VulcanizableChlorinated Elastomer Compositions with Improved Processing Safety,” theteachings of which are incorporated by reference herein as if reproducedin full hereinbelow.

The instant invention relates to an improved cure system composition anda method for curing chlorinated elastomer compositions.

Chlorinated elastomers may be cured by numerous means including the useof peroxide/coagent systems, thiadiazole-based systems, or irradiationcrosslinking techniques. Peroxide cures are typically preferred fortheir scorch safety, shelf-life or bin stability, low permanent set, andhigh temperature performance. However, peroxide cure systems are oftenunacceptable for use in molded goods because of mold sticking andfouling due to volatiles or in applications that require a lowtemperature cure due to equipment or processing limitations.

Thiadiazole-based cure systems provide certain advantages such as theability to cure over a wider range of temperature and pressureconditions than peroxide cures while generating fewer volatilebyproducts, having good mold release characteristics, and the ability touse less expensive compounding ingredients such as aromatic oils.

U.S. Pat. No. 4,128,510 discloses that halogen containing polymers canbe crosslinked by employing a cure system including2,5-dimercapto-1,3,4-thiadiazole (or its derivatives) and a basicmaterial such as a metal oxide, metal hydroxide, or metal carboxylate.It further discloses that the addition of an accelerator containingaliphatic or aromatic amines or quaternary nitrogen groups may bedesirable; additionally, the condensation product of butyraldehyde andaniline is described as being a particularly useful accelerator.

U.S. Pat. No. 4,288,576 discloses 2,5-dimercapto-1,3,4-thiadiazole (andderivatives thereof) curing systems for saturated halogen containingelastomers, for example chlorinated polyethylene, wherein the curingsystems specifically include certain vulcanization accelerators. Classesof accelerators include: 1) amines having a boiling point above 110° C.and pK values below about 4.5; 2) salts of amines with pK values below4.5 and acids having pK values above 2.0; 3) quaternary ammoniumhydroxides and their salts with acids having a pK above 2.0; 4)diphenyl- and ditolyl-guanidines; and 5) the condensation product ofaniline and mono-aldehydes containing one to seven carbon atoms. Thepresence of at least an equal amount of an inorganic base isadditionally required.

Despite the excellent vulcanizate properties obtainable with thepolymercapto/inorganic base/accelerator-based vulcanization systems forchlorinated elastomers, two key problems remain that limit theirusefulness. The first problem is the premature vulcanization of thecompound during storage (that is, poor bin stability) or duringprocessing (that is, poor scorch safety) prior to forming the vulcanizedarticle. The second problem is the inconsistency of the vulcanizationrate. It is desired that the elastomer compound, after preparation, bestable under typical environmental conditions of storage and duringprocessing of the compound such that minimal vulcanization occurs priorto formation of the finished article. A consistent vulcanization rate isdesired so that processes that form the finished vulcanized article, forexample injection molding, extrusion, or compression molding can be runconsistently and without the generation of scrap materials.

U.S. Pat. No. 4,745,147 discloses curable compositions of a chlorinatedpolyethylene, a polymercapto crosslinking agent, an acid acceptor, and apolyhydric alcohol. The composition must also contain a cure initiatorsuch as an amine, a quaternary ammonium salt or a quaternary phosphoniumsalt (collectively hereinafter referred to as “onium salt”). The oniumsalts are of either the formula R₁R₂R₃R₄Z⁺Cl⁻ or the chloride salt of anN-substituted pyridinium ion, wherein Z is N or P; R₁-R₄ may be the sameor different from each other and selected from C₁₋₁₇ alkyl, cyclohexyl,phenyl and benzyl groups. The polyhydric alcohol is said to improve thecure state and heat aging of crosslinked compositions.

U.S. Pat. Nos. 5,665,830 and 5,686,537 disclose that variability in thepremature curing (scorch) of the 2,5-dimercapto-1,3,4-thiadiazole,amine/quaternary ammonium salt, metal oxide cure system is due to theinfluence of water and that the variation can be eliminated by additionof polyethylene glycol or glycerin.

U.S. Pat. No. 4,482,681 discloses polymercapto cure systems containingan organic or inorganic base, and a hydrated salt, which releases itswater during curing. The hydrated salt improves the cure rate. Somechlorinated elastomers also require an accelerator, which may be anamine or a quaternary ammonium salt.

Despite the research efforts in developing and improving in the scorchsafety and cure rate reproducibility, there is still a need for furtherimprovement in scorch safety while maintaining an acceptable cure rate.

The instant invention is an improved cure system composition and amethod for curing chlorinated elastomer compositions. The cure systemcomposition includes a polymercapto crosslinking agent, an inorganicbase, and an onium salt. The onium salt has a formula selected from thegroup consisting of

wherein Z is a nitrogen or phosphorous atom, R₁ to R₄ are independentlyalkyl or aryl groups containing between 2 and 8 carbon atoms, and thetotal number of carbon atoms on R₁-R₄ is between 10 and 14; wherein R₅and R₆ are alkyl groups containing between 1 and 8 carbon atoms, and thetotal number of carbon atoms on R₅-R₆ being between 5 and 9; and whereinX is an anion. The method for curing a chlorinated elastomer compositionaccording to instant invention includes the following steps: (1)providing a chlorinated elastomer composition; (2) providing a curesystem composition as described above; (3) contacting said chlorinatedelastomer composition with said cure system composition; and (4) therebycuring said chlorinated elastomer composition.

The cure system composition according to instant invention includes apolymercapto crosslinking agent, an inorganic base, and an onium salt.Additionally, a curable chlorinated elastomer according to instantinvention includes a chlorinated elastomer, and a cure systemcomposition including a polymercapto crosslinking agent, an inorganicbase, and an onium salt.

Any polymer or copolymer containing chlorine atoms, which can becompounded to form an elastomeric product after crosslinking, can beconsidered a chlorinated elastomer for the purposes of this invention.Examples of chlorinated elastomers include, but are not limited to,polychloroprene, polyepichlorohydrin, epichlorohydrin/ethylene oxidecopolymers, chlorosulfonated polyethylene, chlorinated butyl rubber, andchlorinated polyethylene. Chlorinated and chlorosulfonated polyethyleneare especially preferred in the compositions of this invention becausesuch elastomers are more difficult to dehydrochlorinate than the otherelastomers listed above; thus, they are more sensitive to differences inaccelerator.

Inorganic bases suitable for use in the compositions of this inventioninclude, but are not limited to, metal oxides, metal hydroxides, ortheir salts with weak acids. The inorganic base acts as an acid acceptorto capture the hydrochloric acid that is formed as a byproduct of thecuring reaction. Typical metals include, but are not limited to, thoseof Group IIA of the Periodic Table, such as Mg, Ca, or Ba. Specificexamples of these compounds include, but are not limited to, magnesiumoxide, magnesium hydroxide, calcium oxide, calcium hydroxide, bariumhydroxide, magnesium carbonate, calcium carbonate, barium carbonate.Preferred basic metal oxides and hydroxides are magnesium oxide andmagnesium hydroxide. The basic metal oxides are generally incorporatedat levels of 2-10 parts per hundred parts (phr) of the chlorinatedelastomer.

Polymercapto crosslinking agents, as used herein, refers to crosslinkingagents, which contain at least two —SH groups. These crosslinking agentsmay sometimes be referred to as curing agents or vulcanizing agents.Specific examples of polymercapto crosslinking agents that may beemployed in the compositions of this invention include, but are notlimited to, 2,5-dimercapto-1,3,4-thiadiazole, and its derivatives asdescribed in U.S. Pat. No. 4,128,510; 1,3,5-triazine-2,4,6-trithiol andits derivatives; dimercaptotriazoles as described in U.S. Pat. No.4,234,705; 2-4-dithiohydantoins as described in U.S. Pat. No. 4,342,851;and 2,3-dimercapto-pyrazine or -quinoxalines as described in U.S. Pat.No. 4,357,446. Preferably, the crosslinking agent is2-mercapto-1,3,4-thiadiazole-5-thiobenzoate. The polymercapto compoundis typically incorporated at levels from 0.5 to 5 parts per hundredparts (phr) of the chlorinated elastomer.

Vulcanization accelerators useful in the compositions of this inventionare quaternary ammonium or phosphonium (onium) salts having the generalformula selected from the group consisting of

wherein Z is either a nitrogen atom or a phosphorous atom, each of R₁₋₄is independently an alkyl or aryl group containing between 2 and 8carbon atoms and wherein the total number of carbon atoms on R₁₋₄ isbetween 10 and 14 carbons, R₅ and R₆ are alkyl groups containing between1 and 8 carbon atoms and the total number of carbon atoms on R₅-R₆ isbetween 5 and 9. Preferred aryl groups are benzyl or phenyl. The anion,X⁻, of the onium salt may include, but is not limited to, chloride,bromide, hydrogen sulfate, acetate, fluoride, dihydrogen phosphate, andother anions, which form stable quaternary ammonium or phosphoniumsalts. Aromatic heterocyclic quaternary ammonium and phosphonium salts,wherein the nitrogen or phosphorous atom is part of the ring, are notconsidered accelerators for use in the compositions of this invention.Particularly useful quaternary ammonium compounds aretetrapropylammonium bromide and triethylhexylammonium bromide.

Compositions of the present invention may include other ingredientscommonly employed in rubber vulcanization such as fillers, extenders,plasticizers, stabilizers, and pigments. The properties of the finalvulcanizate can be adjusted by addition of these materials to suit theapplication. Examples of common fillers are calcium carbonate, carbonblack, or clay. Extenders and plasticizers are usually aromatic ornapthenic oils or esters. A typical pigment is titanium dioxide.

The curable compositions of this invention have a combination of goodprocess safety (low scorch and good bin stability) and relatively fastand reproducible cure rates. Typically a scorch rate (see Test Methods)of less than 0.35 Mooney units (MU) per minute is considered safe. Acure rate (see Test Methods) of at least 3 in-lb per minute (3.4dN·m/minute) is considered acceptable. The ratio of cure rate to scorchrate is a convenient parameter that may be employed to describe a curesystem. For most processes, a ratio of at least 13 in-lb/MU (14.7dN·m/MU) is acceptable.

Typical end use applications for the curable compositions of thisinvention include automotive and industrial hose, wire and cablejackets, vibration isolators, flexible boots for mechanical joints,roller covers, seals, and gaskets.

The ingredients of the curable chloroelastomer composition are typicallymixed and uniformly blended with the chlorinated elastomeric polymer byuse of a high intensity internal mixer such as a Banbury® (FarrelCorporation) mixer. They may also be incorporated by milling on a tworoll mill or by any other mechanical mixing device from which a uniformblend of the ingredients can be derived. It is preferable to mix theingredients of the elastomeric composition such that the temperature ofthe composition does not exceed about 110° C. and the time of the mixingis maintained as short as is necessary to achieve a uniform composition.

The mixing process may be improved by adding some of the ingredients ina binder. For example, reaction accelerators can be bound in a polymersuch as ethylene-propylene-diene rubber at concentrations of 25-75percent of the accelerator, thus making addition of small amounts ofingredient easier to handle. Whether the ingredients are added neat orin binders does not materially affect the results of this invention.

The conditions under which the elastomeric compound is crosslinked intothe elastomeric product range from temperatures of from 130° C. to 200°C. and from atmospheric to high pressures, such as those encountered incompression or injection molding. The time for the crosslinking reactionto take place varies with the temperature and the concentrations ofpolymercapto compound, accelerator, and metal oxide in the composition.Lower temperatures and lower concentrations require longer times for thefinished part to be crosslinked. Typical crosslinking times may be from1 minute to several hours.

Test methods include the following:

Cure rate testing was accomplished according to ASTM D2084 on a MonsantoOscillating Disk Rheometer (ODR) at 177° C. for 30 minutes.

Evaluation for processing safety was accomplished according to ASTMD1646 on a Monsanto MV2000E using changes in the Mooney viscosity overthe course of a 25 minute test at 121° C.

For the ODR testing, ML and MH refer to the minimum and maximum torquesmeasured during the test. The t2, t50, and t90 parameters are the timefor the torque to change 2 percent, 50 percent, and 90 percent of thedifference between MH and ML.

The maximum cure rate was obtained directly from the slope of the ODRcurve by calculating the slope of the curve from point to point andtaking the maximum value of the slope.

For the Mooney Scorch test used to estimate processing safety, MooneyMinimum refers to the minimum viscosity observed during the test. Theparameters t3, t5, and t10 refer to the time for the Mooney Viscosity torise by 3, 5, and 10 units respectively. A scorch rate can be calculatedby dividing 2 by the difference between t5 and t3. However, if theMooney viscosity fails to change more than 3-5 units during the test, ascorch rate can be calculated using the following Equation 1.Scorch Rate=(Mooney Viscosity@25 min−Mooney Minimum)/(25 min−time@MooneyMinimum)  Equation 1

EXAMPLES

The following examples illustrate the present invention but are notintended to limit the scope of the invention. The examples of theinstant invention demonstrate that high vulcanization rates can bemaintained while improving the processing safety of the compound bychoosing the quaternary ammonium or phosphonium salt accelerator inaccordance with the present invention.

Examples 1-4 and Comparative Examples A-J

Each of the compositions in Tables I and III was mixed using a Banbury®BR (Farrel Corporation) internal mixer. The dry ingredients were chargedto the mixer first, followed by the liquid ingredients, and then thechlorinated elastomer. A slow mixing speed was used. The Banbury chutewas swept down after the compound had fluxed, and was dumped from themixer at 105° C. The compound discharged from the mixer was placed on a15.24 cm×33.02 cm (6 inch×13 inch) two-roll mill and was rolled as itcame off the mill. This mill procedure was repeated an additional 5-6times to ensure adequate dispersion of all the ingredients. The finalsheet was obtained from the mill in a thickness of approximately 3 mm.Samples cut from this final sheet were used to measure cure rates, andprocessing safety of the compositions. All quaternary ammonium saltswere added such that 0.001 moles of the quaternary ammonium salt wasused per 100 grams of the rubber used in the composition.

TABLE I Comp. Comp. Comp. Comp. Comp. Comp. Comp. Example ExampleExample Example Example Example Example Example Example Ingredient 1,phr 2, phr A, phr B, phr C, phr D, phr E, phr F, phr G, phr ChlorinatedPolyethylene¹ 100 100 100 100 100 100 100 100 100 Carbon Black² 50 50 5050 50 50 50 50 50 Magnesium Hydroxide³ 5 5 5 5 5 5 5 5 5 Aromatic Oil⁴30 30 30 30 30 30 30 30 30 2-mercapto-1,3,4-thiadiazole-5- 2.67 2.672.67 2.67 2.67 2.67 2.67 2.67 2.67 thiobenzoate⁵ Triethylhexylammoniumbromide⁶ 0.27 Tetrapropylammonium bromide⁷ 0.27 Tetrabutylammoniumbromide⁸ 0.66 Tetrahexylammonium bromide⁹ 0.45 Tetraheptylammoniumbromide¹⁰ 0.5 Tetraethylammonium bromide¹¹ 0.21Octadecyltrimethylammonium 0.4 bromide¹² Methyltrioctylammoniumbromide¹³ 0.46 Didecyldimethylammonium bromide¹⁴ 0.42 ¹Tyrin ® CM0836available from DuPont Dow Elastomers L.L.C. ²N-774 available from SidRichardson Carbon Co. ³StanMag ® Hydroxide B available from Harwick⁴Sundex ® 790T available from Sunoco, Inc. ⁵Mastermix ® MB 4842 (75percent active) available from Harwick ^(6-7,9-13)Available from Aldrich⁸Mastermix ® MB 4988 (50 percent active) available from Harwick

The cure rate and processing safety data of compositions containingquaternary ammonium bromides as accelerators, Examples 1 and 2, andComparative Examples A-G are listed in Table II. The ratio of themaximum cure rate/scorch rate can be used to estimate the quality of theaccelerator. Accelerators that give fast cure rates but good processingsafety will have high ratios. From Table II, it can be clearly seen thatthe Examples of the present invention have the highest ratios of curerate/scorch rate and are preferred accelerators.

TABLE II Example Example Comparative Comparative Comparative ComparativeComparative Comparative Comparative Property 1 2 Example A Example BExample C Example D Example E Example F Example G ML min (in-lb) 13.4414.03 14.54 15.44 17.34 12.72 12.72 15.21 13.88 MH max (in-lb) 47.7346.77 51.98 56.98 59.25 35.68 44.21 52.65 46.89 t2 (minutes) 1.3 1.281.03 0.89 0.86 2.19 1.88 1.03 1.37 t50 (minutes) 4.46 4.33 3.24 2.772.45 10.6 10.6 4.44 8.24 t90 (minutes) 12.51 13.06 8.74 7.51 7.34 21.1121.15 16.47 19.88 Max Cure Rate 6.14 6.11 9.56 11.42 14.50 1.37 1.857.03 3.40 @177 C. (in-lb/min) Mooney minimum, 35.4 36.2 37.8 38.6 42.635.5 35 39.2 36.4 121° C., MU t3, min 15.8 13 7.85 5.79 4.68 18.9 6.629.17 t5, min 20.3 10.18 7.02 5.7 8.14 12.08 t10, min 17.27 10.18 8.1712.12 20.75 Scorch Rate at 0.258 0.276 0.858 1.626 1.961 0.110(est.)*0.205(est.)* 1.316 0.687 121° C., 2/ (est.)* (t5 − t3), MU/min Max CureRate 23.8 22.15 11.14 7.02 7.40 12.45 9.02 5.34 4.95 at 177° C./ ScorchRate at 121 C. (in-lb/MU) *The scorch rate was estimated by the slope ofthe Mooney Scorch Curve since t5 > 25 minutes

TABLE III Comp. Comp. Comp. Example 3, Example 4, Example H, Example I,Example J, Ingredient phr phr phr phr phr Chlorinated Polyethylene¹ 100100 100 100 100 Carbon Black² 50 50 50 50 50 Magnesium Hydroxide³ 5 5 55 5 Aromatic Oil⁴ 30 30 30 30 30 2-mercapto-1,3,4-thiadiazole-5- 2.672.67 2.67 2.67 2.67 thiobenzoate⁵ Tetrapropylammonium chloride⁶ 0.23Tetrapropylammonium iodide⁷ 0.32 Tetraethylammonium iodide⁸ 0.26Tetrabutylatnmonium chloride⁹ 0.28 Tetrabutylammonium iodide¹⁰ 0.38¹Tyrin ® CM 0836 available from DuPont Dow Elastomers L.L.C. ²N-774available from Sid Richardson Co. ³StanMag ® Hydroxide B available fromHarwick ⁴Sundex ® 790T available from Sunoco, Inc. ⁵Mastermix ® MB 4842(75 percent active) Available from Harwick ^(6-7,9-10)Available fromAldrich ⁸available from Harwick

Additional examples were prepared using tetrapropylammonium chloride andiodide versus comparative examples containing tetraethylammonium iodideand tetrabutylammonium chloride and iodide. The composition of Examples3 and 4, and that of Comparative Examples H, J, and I are listed inTable III. The cure rate and processing safety data for thesecompositions are listed in Table IV. The ratio of the maximum curerate/scorch rate is clearly higher for the examples of the presentinvention.

TABLE IV Comparative Comparative Comparative Property Example 3 Example4 Example H Example I Example J ML min (in-lb) 14.73 11.87 11.02 16.5315.2 MH max (in-lb) 48.57 43.35 26.89 53.93 51.55 t2 (minutes) 1.13 1.842.72 0.93 1.01 t50 (minutes) 3.88 7.38 14.18 2.77 3.15 t90 (minutes)12.58 19.92 26.39 7.89 8.5 Max Cure Rate @177° C. (in-lb/min) 6.96 3.070.66 10.89 6.43 Mooney minimum, 121° C., MU 36.7 34.3 33.8 39.8 37.2 t3,min 11.4 19.9 5.95 7.55 t5, min 17.13 7.45 9.73 t10, min 11.78 15.47Scorch Rate at 121° C., 2/(t5 − t3), 0.347 0.23(est.)* 0.093(EST.)* 1.330.917 MU/min Max Cure Rate at 177° C./Scorch 20.04 13.35 7.10 8.17 7.01Rate at 121° C. (in-lb/MU) *The scorch rate was estimated by the slopeof the Mooney Scorch Curve since t5 > 25 minutes.

Examples 5-8

Compositions of the invention containing pyrollidinium chlorides orbromides as cure accelerators were made by the same process that wasemployed to prepare Examples 1-4 above. The formulations are shown inTable V. Cure rate and processing safety parameters are given in TableVI.

TABLE V Example 5, Example 6, Example 7, Example 8, Ingredient phr phrphr phr Chlorinated Polyethylene¹ 100 100 100 100 Carbon Black² 50 50 5050 Magnesium Hydroxide³ 5 5 5 5 Aromatic Oil⁴ 30 30 30 302-mercapto-1,3,4-thiadiazole-5-thiobenzoate⁵ 2.67 2.67 2.67 2.671-butyl-1-methylpyrollidinium bromide⁶ 0.231-butyl-1-methylpyrollidinium chloride⁷ 0.191-hexyl-1-methylpyrollidinium chloride⁸ 0.221-octyl-1-methylpyrollidinium chloride⁹ 0.25 ¹Tyrin ® CM 0836 availablefrom DuPont Dow Elastomers L.L.C. ²N-774 available from Sid RichardsonCo. ³StanMag ® Hydroxide B available from Harwick ⁴Sundex ® 790Tavailable from Sunoco, Inc. ⁵Mastermix ® MB 4842 (75 percent active)available from Harwick ⁶⁻⁹Available from Aldrich

TABLE VI Test Parameter Example 5 Example 6 Example 7 Example 8 ML min(in-lb) 12.06 12.49 12.72 13.75 MH max (in-lb) 42.08 44.34 45.95 48.93t2 (minutes) 2.29 1.99 1.71 1.45 t50 (minutes) 9.73 8.6 7.34 6.33 t90(minutes) 21.01 19.77 18.28 16.75 Max Cure Rate 2.5 2.64 3.17 3.87 @177°C. (in-lb/min) Mooney minimum, 33.9 34.5 34.4 121° C., MU t3, min 19.2214.4 t5, min 21.15 t10, min Scorch Rate 0.111* 0.108* 0.166* 0.269* at121° C., 2/(t5 − t3), MU/min Max Cure Rate 22.5 24.5 19.1 14.4 at 177°C./ Scorch Rate at 121° C. (in-lb/MU)

1. A cure system composition comprising: a polymercapto crosslinkingagent selected from the group consisting of2,5-dimercapto-1,3,4-thiadiazole, and a derivative thereof; an inorganicbase; and an onium salt selected from the group consisting oftetrapropylammonium bromide, and triethylhexylammonium bromide.
 2. Acurable chlorinated elastomer composition comprising: a chlorinatedelastomer; a polymercapto crosslinking agent selected from the groupconsisting of 2,5-dimercapto-1,3,4-thiadiazole, and a derivativethereof; an inorganic base; and an onium salt selected from the groupconsisting of tetrapropylammonium bromide, and triethylhexylammoniumbromide.
 3. The curable chlorinated elastomer composition according toclaim 2, wherein said chlorinated elastomer is selected from the groupconsisting of polychloroprene, polyepichlorohydrin,epichlorohydrin/ethylene oxide copolymers, chlorosulfonatedpolyethylene, chlorinated polyethylene, and chlorinated butyl rubbers.4. The curable chlorinated elastomer composition according to claim 3,wherein said chlorinated elastomer is chlorinated polyethylene.
 5. Amethod of curing a chlorinated elastomer composition comprising thesteps of: providing a chlorinated elastomer composition; providing acure system composition comprising: a polymercapto crosslinking agent;an inorganic base; and an onium salt selected from the group consistingof tetrapropylammonium bromide, and triethylhexylammonium bromide;contacting said chlorinated elastomer composition with said cure systemcomposition; and thereby curing said chlorinated elastomer composition.6. The method of curing a chlorinated elastomer composition according toclaim 5, wherein said chlorinated elastomer composition and said curesystem composition are admixed.
 7. The method of curing a chlorinatedelastomer composition according to claim 5, wherein said contacting stepis conducted at a temperature in the range of 130° C. to 200° C.
 8. Themethod of curing a chlorinated elastomer composition according to claim5, wherein said chlorinated elastomer is selected from the groupconsisting of polychloroprene, polyepichlorohydrin,epichlorohydrin/ethylene oxide copolymers, chlorosulfonatedpolyethylene, chlorinated polyethylene, and chlorinated butyl rubbers.9. The method of curing a chlorinated elastomer composition according toclaim 8, wherein said chlorinated elastomer is chlorinated polyethylene.